Karsen, I am not able to see any image/attachment with your post. Can
you please attach that ?
When I tried recreating using your snippet on Gtk2.6, I have seen the
appearance of toolItem as expected without any problem.

You should be able to see the attachment here.. But that is in fact the same URL as in my initial posting, so you might not see the image either. If so, I might try and send you a PM or an e-mail with the image attached.